The materials and/or alloys of sputtering targets have inherent characteristics that are a result of target manufacturing processes. These characteristics, for example, target density, sputtered particle performance, and uniformity, have an effect on the end use of the target. One undesirable effect of target manufacture is a lack of early life uniformity as measured on a wafer as used in the semi-conductor industry. Typically, sputtering targets made from aluminum, and various alloys thereof, exhibit a sputtered film uniformity of 0-3% deviation of sheet resistance as measured by a four-point resistivity probe on a 6 inch wafer. The acceptable range for such deviation is 0-1.67% per 6 inch wafer. Any improvement in uniformity would reduce rejects at the customer site. Further, an improvement in early life uniformity will increase the utilization of the sputtering targets and increase sputtering tool productivity.
Another undesirable effect of target manufacture is unwanted particles on a wafer generated during sputtering. Typically, targets made from W/Ti 10% using standard powder metallurgy processes exhibit high particle counts greater than 10 particles &gt;0.3 micrometer size per 6 inch wafer. This also causes a relatively high rejection rate of wafers.
The previous efforts to achieve particle reduction and early life uniformity have proved costly and ineffective. Unaccountable variances in target manufacturing directly affect product end use characteristics. Sputtering targets of marginal acceptance are scrapped. There is a need to improve sputtering target characteristics while maintaining the cost efficient metallurgical processes for manufacturing high performance targets.